Why Heat Pump Water Heaters?
By Positive Energy staff
Clients want reliable hot water that is available when they want it.
They are agnostic as to how their hot water is produced. Builders and their installing contractors (mechanical and plumbing) are not agnostic, they prefer to do what they’ve always done. It’s important and in the benefit of owners to have a forward facing, rather than a backward facing (“always done it this way”) perspective. Human society is currently undergoing an inexorable global energy transition off of fossil fuels and on to renewable electricity; all involved need to recognize this and factor it into decision making.
Heat pump water heaters are reliable, mature technologies.
Your home’s refrigerator is a heat pump. Unfortunately some of the early entrants in the HPWH category in the US in the early 2010s (approx. 2011-2015) had reliability issues, mostly on the controls side, but still the damage was done and the reflexive stigma remains, inappropriately, in place today. Broadly speaking builders and installing contractors have been reluctant to update their opinions and judgements. The current suite of mature HPWH technologies from AO Smith, Rheem, Sanden, Stiebel Eltron, and many others are simply water heating appliances, they are stocked in distribution warehouses all over the US. The time is now for builders and installers to embrace them for the benefit of all involved.
Gas water heating is an obsolete technology that is still around.
Setting owners up for ongoing future reliance on fossil fuels is not supported by an informed forward looking perspective. The practice of using fossil fuel combustion appliances in homes is currently and rapidly being written out of the plans for society. Beyond not recommending them, there are already legislative and regulatory agendas in place that make fossil fuel based water (and space) heating illegal in the future.
HPWHs are the sensible choice for heating water.
Heat pump water heaters leverage otherwise unusable waste heat in the ambient air and convert it to a high quality source for heating water (also for heating air in the home). Gas water heaters rely on destroying a precious, finite, high energy density fossil fuel that is critically needed for industrial grade heating applications. Using an industrial grade fossil fuel source for a low grade residential application is nonsensical and completely unnecessary. Selecting a gas water heater also represents a long term commitment to destroying fossil fuels and putting the waste carbon in the sky for the life of the home, or until an inconvenient, costly future remodel.
Let the numbers tell the story
Heat pump water heaters operate at energy efficiencies over the range of 300 to 550%. Yes, really. One unit of electrical energy in provides up to 5.5 units of thermal energy out. The other option is to use a gas water heater at up to 96% efficiency. Note that this 96% is only the efficiency of releasing the thermal content of the fuel during the combustion process. The fact that gas has been (relatively) easy to find and burns readily does not offset the reality that using a 3500F gas flame to heat water to 120-140F or air to 65-75F is in no way and has never been thermodynamically efficient.
Have a back up plan
If it becomes untenable for the project team and a builder or installing contractor can not be persuaded, at the very least have circuits provision in the electrical panel with wiring run from the panel to the air handler and water heater areas. The power of traditional practices is strong. Society has been asking builders and trades “how fast and how cheap” for decades. With those as primary sorting functions it not surprising that these folks advocated for fossil fuels.
Doctors used to smoke and appear in cigarette advertisements.
Burning fossil fuels, destroying them forever and putting the waste carbon in the sky is currently poised on the edge of being that thing that we look back on and wonder why and how we did it for so long. There is no question that the 100 year plus propaganda campaign the Petrochemical Industry has enacted on the US Public has been effective at maintaining fossil fuel hegemony. In spite of this, there is also no question that society is moving away from reliance on fossil fuels. Looking forward we see that the global economy* is moving from finite fossil fuels for space and water heating to using electric sources based on simple reliable renewable energy technologies.
*We are just now entering an era in society where we are running out of economically viable access to fossil fuels. There are reserves in the ground, but it does not make sense economically to go get them because the same energy can be produced more cheaply, with lower operating costs for power producers and no fossil fuel combustion emissions. These stranded fossil fuel assets will lead to a near term impact on the availability and pricing for fossil fuels as well as nearly all aspects of the economy. Fossil fuels are a master commodity, one that implicitly impacts everything we manufacture and transport as part of economic activity.